FOX News teamed up with Facebook on Thursday for the first prime-time GOP presidential primary debate of the 2016 election cycle. Ten Republican contenders squared off on-stage in Cleveland during the FOX News-Facebook Debate, answering a mix of questions including ones sourced directly from people on Facebook.

The event sparked strong social conversation with 7.5 million people generating more than 20 million Facebook posts, comments, and likes. Many turned to Facebook to comment on the candidates’ performances and discuss issues of importance, as the voices and faces of people on the platform framed the questions and tone of this early #GOPDebate.

The most-talked-about moment of the night was a spirited exchange between Sen. Rand Paul and Gov. Chris Christie over issues of government surveillance. Real estate magnate Donald Trump, who was the frontrunner heading into the debate, was the most-talked about candidate on Facebook, followed by neurosurgeon Ben Carson. Immigration and racial issues were the hottest topics, according to Facebook’s data team. Check out how the other candidates and issues ranked in Facebook conversation:

Most-mentioned candidates

Donald Trump

Ben Carson

Rand Paul

Mike Huckabee

Chris Christie

Most-discussed issues

Immigration

Racial issues

The economy

Education

Abortion

During the debate, the candidates responded to questions directly from people on Facebook, including Facebook Video submissions. This was the result of a month-long, call-to-action campaign that generated nearly six million views and received more than 40,000 responses. FOX News asked viewers to submit their “one question” for the candidates. These videos and posts elicited powerful, personal responses that were incorporated directly into questions from the moderators.

FOX News used a Video Uploader, powered by Telescope, to allow fans to submit questions on their page. Fans submitted text, photos & videos; FOX News then utilized a moderation tool to review & select questions. Learn more about these tools for broadcasters here.

FOX correspondent Shannon Bream summarized Facebook data on FOX programming throughout the day on Thursday in the lead-up to the main event. She used a specially-designed touchscreen monitor to highlight the volume and demographic breakdown of the political conversation on Facebook across the country. Bream was the first to report the most-talked-about candidate during the debate in FOX’s post-show coverage as well.

Instagram featured the candidates’ accounts on the platform’s Explore tab in a special GOP debate collection, marking its first engagement in the 2016 election. The candidates shared a behind-the-scenes look at everything from their preparation and pre-debate rituals, to late night scenes from the spin room. Highlights included Sen. Ted Cruz backstage with his “two best advisors” (his two young daughters), and Sen. Rick Santorum watching the prime-time debate with former New York Gov. George Pataki and Texas Gov. Rick Perry.

Donald Trump live-streamed his arrival in Cleveland using Live for Facebook Mentions, Facebook’s new live video product for public figures. Nearly two million people viewed it, chiming in with 18,000 comments, more than 88,000 likes, and over 9,000 shares at the time this post was published. Dr. Ben Carson answered questions about everything from his first job to his sleeping habits in a rapid-fire Q&A from the Facebook Lounge that was viewed over 300,000 times. Pundits and personalities such as Newt Gingrich and Karl Rove also live-streamed throughout the day.

Before, during and after this first, prime-time GOP debate, Facebook was the clear destination for political conversation. The race to the White House is just heating up, so join the conversation on Facebook to keep up with the candidates and issues that matter most to you.